Measurement-sensing device for determining a rotational speed or rotational speed change, preferably of vehicle wheels

ABSTRACT

A measurement sensing device for detecting a rotational speed or rotational speed change, particularly of vehicle wheels, which essentially consists of a rotor and of a stator constructed as magnet and equipped with an annular coil, whereby an A.C. voltage proportional to the rotational speed is induced in the stator by the rotation of the rotor; the rotor and stator are thereby so combined into a structural unit that the rotor is so rotatably supported relative to the stator at the latter or at a part connected therewith that during operation no changes in radial or axial spacing between rotor and stator occur.

United States Patent Kruse [54] MEASUREMENT-SENSING DEVICE FORDETERMINING A ROTATIONAL SPEED OR ROTATIONAL SPEED CHANGE, PREFERABLY OFVEHICLE Foreign Application Priority Data Dec. 10, 1969 Germany ..P 1961 846.3

U.S. Cl. ..310/168, 310/90, 310/171 Int. Cl. ..H02k 17/42 Field ofSearch ..310/158, 159, 90, 166, 168, 310/169, 170,171, 268, 66, 67

1 Aug. 8, 1972 Primary ExaminerJ. D. Miller Assistant Examiner-R. SkudyAttorney-Craig, Antonelli and Hill [57] ABSTRACT A measurement sensingdevice for detecting a rotational speed or rotational speed change,particularly of vehicle wheels, which essentially consists of a rotorand of a stator constructed as magnet and equipped with an annular coil,whereby an A.C. voltage proportional to the rotational speed is inducedin the stator by the rotation of the rotor; the rotor and stator arethereby so combined into a structural unit that the rotor is sorotatably supported relative to the stator at the latter or at a partconnected therewith that during operation no changes in radial or axialspacing between rotor and stator occur.

20 Claims, 2 Drawing Figures INVENTOR WERNER KRUSE BY mm, SwamiATTORNEYS MEASUREMENT-SEN SING DEVICE FOR DETERMINING A ROTATIONAL SPEEDOR ROTATIONAL SPEED CHANGE, PREFERABLY OF VEHICLE WHEELS The presentinvention relates to a measurement detecting device which is preferablycoordinated to a vehicle wheel and which produces pulses proportional tothe wheel rotational speed. These pulses may be utilized in acorresponding electronic device for the control of an anti-lockingmechanism, of a starting or acceleration swerving protection or of atachometer.

Installations are already known which produce pulses or signalsproportional to the rotational speed. They operate either hydraulically,mechanically, optically or inductively. The inductive measurementtransmitting devices are particularly suited for the installation at thevehicle wheel since they operate contactless, i.e., without physicalcontact. With known types of construction of such devices a disk whichis toothed at the outer circumference, is mounted on a shaft or at thewheel hub. To this disk, which may also be designated as rotor, iscoordinated a stationary or fixed magnet (stator). The magnetic flux ofthis magnet is changed by the rotating toothed disk whereby analternating current voltage is induced at the stator whose frequency isproportional to the wheel rotational speed. The distance between statorand rotor must thereby change only very slightly for a constant pulsesequence as otherwise the pulses are missing or the pulse transmitter isdestroyed in effect in case of contact of stator and rotor. Many axleconstructions make impossible an accurate constant distance betweenstator and rotor. In

order to ensure the proper functioning and operation of ble. With manyaxle constructions, a subsequent instalv lation is possible only aftervery extensive constructive changes by reason of the large spacerequirement.

The present invention aims at so constructing an inductive measurementdetecting device that it remains uninfluenced by shaft deflections oroscillations and can be accommodated within a protected space.

As solution to the underlying problem, a measure- I ment sensing devicefor the determination of a rotational speed or of a rotational speedchange, preferably of vehicle wheels, is proposed which essentiallyconsists of a rotor and of a stator constructed as magnet and equippedwith a ring coil, whereby an AC. voltage proportional to the rotationalspeed is induced in the rotor by the rotation of the stator, in whichaccording to the present invention the rotor and stator are so combinedinto a structural unit that the rotor is rotatably supported relative tothe stator at the latter or at a part connected therewith in such amanner that during the operation no radial or axial changes in spacingbetween rotor and stator occur.

The rotary movement is thereby transmitted to the rotor preferably by anelastic entrainment member which is constructed as leaf spring.

According to a particularly preferred embodiment of the presentinvention, the rotor and stator are provided at mutually opposite endfaces with end teeth that do not contact one another, whereby an axialfriction or sliding bearing is formed by layers of non-magnetic frictionbearing material applied on the end teeth so that a certain axialdistance of rotor and stator is determined by the layer thicknesses overthe tooth tips.

However, the rotor may also be provided with an internally toothedarrangement and the stator with an externally toothed arrangement orvice versa whereby the toothed arrangements are arranged at such aradial distance that they do not contact one another.

A very large number of pulses can be achieved by such a type ofarrangement and construction of the measuring detecting device since thecorresponding tooth pitch on the rotor and stator can be selected verysmall. The influence of deflections and vibrations or oscillations iscompensated by the elastic entrainment means. The compact type ofconstruction enables the installation in the sealed space of the wheelbearing.

Accordingly, it is an object of the present invention to provide ameasuring detecting device for determining a rotational speed orrotational speed change of vehicle wheels which avoids theaforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a measuring sensingdevice for detecting rotational speeds or rotational speed changes whichpermits the realization of relatively large number of pulses perrotation of the wheel without the danger of damage or faulty operationof the detecting device.

A further object of the present invention resides in a rotational speedsensing device of the type described above which can be accommodatedwithin a protected, sealed space to avoid soiling and prevent harmfulexternal influences on the device.

A still further object of the present invention resides in a measurementsensing device for detecting rotational speeds of vehicle wheels orchanges in the rotational speeds thereof which can be readily installedinto existing axle constructions yet is substantially immune todestruction due to contact between rotor and stator.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, two embodiments in accordance with thepresent invention, and wherein:

FIG. 1 is a partial cross-sectional view through a front axle bearingwith mounted measuring sensing devicein accordance with the presentinvention; and

FIG. 2 is a partial cross-sectional view through a rear aide bearingwith inserted measuring sensing device in accordance with the presentinvention.

Referring now to the drawing, and more particularly to FIG. 1, themeasuring sensing or detecting device generally designated by referencenumeral 1 is mounted over the axle 4 outside of the outer front wheelbearing 2 and of the lock nut 3. The outer end of the axle 4 is providedwith a cylindrical seat or fit 5 and a longitudinal groove 6. Themeasurement sensing device 1 is mounted over the axle 4 up to theabutment of the stator 8 and is secured against rotation by a nose 9 inthe coil body 10 which engages in the longitudinal groove 6. The stator8 is constructed as annular member with U-shaped cross section. The coilbody 10 with the coil winding 11 is inserted on the inside of theU-shaped cross section. The inner leg portion 12 of the stator body 8carries a radial friction bearing 13 on which is supported the rotor 14.This friction bearing 13 consists preferably of a magnetic material inorder to keep smallthe magnetic resistance between stator 8 and rotor14. The friction bearing 13 and the rotor 14 are held on the stator 8 bya snap ring 15.

The outer leg portion 16 of the stator 8 carries at its free end anend-face toothed arrangement or serration 17 whose tooth gaps and toothtips are coated with a non-magnetic friction bearing material so that asmooth surface results which forms an axial friction bearing 18 for therotor 14. The end-face toothed arrangement or serration 19 on the outercircumference of the disk-shaped rotor 14 is coated, in a similar manneras the stator 8, with a friction bearing material that forms the othercontact surface 20 of the axial friction bearing 18. The thickness ofthe two contact surfaces determines the distance between the rotor 14and the stator 8 with the rotor and stator serving as counter contactelements for one another. One or several radially extending grooves 21on the back side of the rotor 14 accommodate the free end of anentrainment member 23 constructed as leaf spring that may have severalarms. Advantageous with the use of a leaf spring is the high rigiditythereof in the direction of rotation. The spring forces need not be alltoo large in the axial direction because the rotor 14 is attractedtoward the stator 8 by the magnetic forces. The entrainment member 23 isnon-rotatably connected by means of two rivets 24 with the screwed-oncap 25 for rotation in unison therewith, which is screwed on the wheelhub 26.

The electrical connection is established appropriately by a coaxialconnector. For that purpose a plug 27 which is secured at a cable 28, isintroduced into an offset bore of the axle 4. The associatedcounter-part 30 of the plug 27 is rigidly molded or cast into the stator8 in any conventional manner. The separating place 31 of the connectoris disposed on the inside of the bore 29 in order that the contacts arenot damaged with a disassembled measuring sensing device.

In FIG. 2, a measuring sensing device generally designated by referencenumeral 32 is illustrated which is installed as structural unit in thewheel carrier 33 between the two bearings 34 and 35. The stator 36 andthe rotor 37 are so constructed that they enclose the coil 38 with thecoil body 39. An end-face toothed arrangement or serration 40 of thestator 36 and an endface toothed arrangement 41 of the rotor 37 areagain covered with a non-magnetic material so that an axial frictionbearing 61 is formed. The L-shaped rotor 37 may carry on its longer legportion a further axial bearing 60 which, however, only serves thepurpose not to interrupt the magnetic circuit by a large air gap.Consequently, the axial bearing 60 is appropriately made from a magneticfriction bearing material. Radially, the rotor 37 is guided by a slidingor bearing ring 42 which is made from non-magnetic material. Thisbearing ring 42 is disposed between the short leg portion of the L-shaped rotor 37 and a tubularly shaped, non-magnetic sheet metal jacketor case 43 which is pressed over the stator 36 and holds together therotor 37 and stator 36 by a flange 44.

The rotor 37 carries at the outer side of its short leg portion 45 aradially extending groove 46 into which engages a leaf spring 47. Theleaf spring 47 is secured at a ring 48 which is non-rotatably mounted onthe shaft 49 for rotation in unison therewith. The ring 48 and leafspring 47 form the entrainment member for the rotor 37.

Two wires 50 lead from the coil 38 through a bore 51 in the stator 36 toa female connector member 52 which is molded-in by means of syntheticresinous material into the bore 53 of the stator 36. The plug 54together with a cable 55 is guided in a threaded bush 56 and is securedby a screw cap 57. The rubber ring 58 forms for the cable 55 a tensionalstress relief and simultaneously seals the plug 54 against moisture fromthe outside. The threaded bush 56 is so constructed that it projectsinto the bore 53 of the stator 36 whereby the stator 36 is fixed in theaxial direction within the wheel carrier 33. The threaded bush 56 issecured by a sheet metal member 59.

While I have shown and described only two embodiments in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible of numerous changes and modifications asknown to those skilled in the art, and I therefore do not wish to belimited to the details shown and described herein but intend to coverall such changes and modifications as are encompassed by the scope ofthe appended claims. I

What I claim is:

1. A measuring sensing device for detecting a rotational speed or arotational speed change, which includes a rotor means and a stator meansconstructed as magnet and having a coil, whereby an A.C. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, and that therotary movement is transmitted to the rotor means by an elasticentrainment means.

2. A measuring sensing device according to claim 1, characterized inthat the entrainment means is constructed as leaf spring.

3. A measuring sensing device for detecting a rotational speed or arotational speed change, which includes a rotor means and a stator meansconstructed as magnet and having a coil, whereby an AC. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, and that therotor means is supported at the stator means by way of first frictionbearing means in the form of a slide bearing providing for the radialguidance thereof and second friction bearing means in the form of aslide bearing providing for the axial guidance thereof.

4. A measuring sensing device according to claim 3, characterized inthat at least one of the friction bearing means consists of aniron-containing material.

5. A measuring sensing device for detecting a rotational speed or arotational speed change, which includes a rotor means and a stator meansconstructed as magnet and having a coil, whereby an AC. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, the rotor andstator means being provided at mutually opposite end-faces with end-facetooth means that do not contact one another, and that an axial frictionbearing means is formed by layers of non-magnetic friction bearingmaterial applied to the end-face tooth means so that a certain axialdistance of rotor and stator means is determined by the layerthicknesses over the tooth tips.

6. A measuring sensing device for detecting a rotational speed or arotational speed change, which includes a rotor means and a stator meansconstructed as magnet and having a coil, whereby A.C. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, one of therotor and stator means being provided with internal tooth means and theother with external tooth means whereby the tooth means are arranged atsuch a radial distance that they do not contact one another, and radialfriction bearing means being formed by layers of non-magnetic frictionbearing material applied over the tooth means for maintaining thedistance between the tooth means.

7. A measuring sensing device for detecting a rotational speed or arotational speed change, which includes a rotor means and a stator meansconstructed as magnet and having a coil, whereby an AC. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, and that atleast one of the two parts consisting of rotor and stator meansessentially consists of a synthetic resinous te 'al ntainm' ir i. R rriesunng en ii'lg device according to claim 7,

characterized in that both rotor and stator means are made fromiron-containing synthetic resinous material.

9. A measuring sensing device for detecting a rotational speed or arotational speed change, which includes a rotor means and a stator meansconstructed as magnet and having a coil, whereby an AC. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, at least oneof the rotor and stator means being partially magnetized, and only thecounter element formed of the other of the two parts consisting of rotorand stator means being provided with a toothed means.

10. A measuring sensing device according to claim 2, characterized inthat the rotor means is supported at the stator means by way of anfriction bearing means which guides the rotor means in the radial andaxial directions.

1 1. A measuring sensing device according to claim 1, characterized inthat the rotor means is supported at the stator means by way of at leastone friction bearing means.

12. A measuring sensing device according to claim 1 1, characterized inthat separate friction bearing means in the form of slide bearings areprovided for the radial and axial guidance.

13. A measuring sensing device according to claim 2, characterized inthat the rotor and stator means are provided at mutually oppositeend-faces with end-face tooth means that do not contact one another.

14. A measuring sensing device according to claim 13, characterized inthat an axial friction bearing means is formed by layers of non-magneticfriction bearing material applied to the end-face tooth means so that acertain axial distance of rotor and stator means is determined by thelayer thicknesses over the tooth tips.

15. A measuring sensing device according to claim 14, characterized inthat a radial friction bearing means is formed by layers of non-magneticfriction bearing material applied over the tooth means.

16. A measuring sensing device according to claim 2, characterized inthat at least one of the two parts consisting of rotor and stator meansessentially consists of a synthetic resinous material containing iron.

17. A measuring sensing device according to claim 2, characterized inthat both rotor and stator means are made from iron-containing syntheticresinous material.

18. A measuring sensing device according to claim 2, characterized inthat at least one of the rotor and stator means is partially magnetized.

19. A measuring sensing device according to claim 2, characterized inthat both rotor and stator means are partially magnetized.

20. A measuring sensing device according to claim 18, characterized inthat only the counter element formed of the other of the two partsconsisting of rotor and stator means is provided with a toothed means.

1. A measuring sensing device for detecting a rotational speed or arotational speed change, which includes a rotor means and a stator meansconstructed as magnet and having a coil, whereby an A.C. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, and that therotary movement is transmitted to the rotor means by an elasticentrainment means.
 2. A measuring sensing device according to claim 1,characterized in that the entrainment means is constructed as leafspring.
 3. A measuring sensing device for detecting a rotational speedor a rotational speed change, which includes a rotor means and a statormeans constructed as magnet and having a coil, whereby an A.C. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, and that therotor means is supported at the stator means by way of first frictionbearing means in the form of a slide bearing providing for the radialguidance thereof and second friction bearing means in the form of aslide bearing providing for the axial guidance thereof.
 4. A measuringsensing device according to claim 3, characterized in that at least oneof the friction bearing means consists of an iron-containing material.5. A measuring sensing device for detecting a rotational speed or arotational speed change, which includes a rotor means and a stator meansconstructed as magnet and having a coil, whereby an A.C. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, the rotor andstator means being provided at mutually opposite end-faces with end-facetooth means that do not contact one another, and that an axial frictionbearing means is formed by layers of non-magnetic friction bearingmaterial applied to the end-face tooth means so that a certain axialdistance of rotor and stator means is determined by the layerthicknesses over the tooth tips.
 6. A measuring sensing device fordetecting a rotational speed or a rotational speed change, whichincludes a rotor means and a stator means constructed as magnet andhaving a coil, whereby A.C. voltage proportional to the rotational speedis induced in the stator means as a result of the rotation of the rotormeans, characterized in that the rotor and stator means are so combinedinto a structural unit that the rotor means is rotatably supportedrelative to the stator means at least on a part connected with saidstator means in such a manner that during the operation substantially nochanges in at least one of the radial and axial distances between rotorand stator means can occur, one of the rotor and stator means beingprovided with internal tooth means and the other with external toothmeans whereby the tooth means are arranged at such a radial distancethat they do not contact one another, and radial friction bearing meansbeing formed by layers of non-magnetic friction bearing material appliedover the tooth means for maintaining the distance between the toothmeans.
 7. A measuring sensing device for detecting a rotational speed ora rotational speed change, which includes a rotor means and a statormeans constructed as magnet and having a coil, whereby an A.C. voltageproportional to the rotational speed is induced in the stator means as aresult of the rotation of the rotor means, characterized in that therotor and stator means are so combined into a structural unit that therotor means is rotatably supported relative to the stator means at leaston a part connected with said stator means in such a manner that duringthe operation substantially no changes in at least one of the radial andaxial distances between rotor and stator means can occur, and that atleast one of the two parts consisting of rotor and stator meansessentially consists of a synthetic resinous material containing iron.8. A measuring sensing device according to claim 7, characterized inthat both rotor and stator means are made from iron-containing syntheticresinous material.
 9. A measuring sensing device for detecting arotational speed or a rotational speed change, which includes a rotormeans and a stator means constructed as magnet and having a coil,whereby an A.C. voltage proportional to the rotational speed is inducedin the stator means as a result of the rotation of the rotor means,characterized in that the rotor and stator means are so combined into astructural unit that the rotor means is rotatably supported relative tothe stator means at least on a part connected with said stator means insuch a manner that during the operation substantially no changes in atleast one of the radial and axial distances between rotor and statormeans can occur, at least one of the rotor and stator means beingpartially magnetized, and only the counter element formed of the otherof the two parts consisting of rotor and stator means being providedwith a toothed means.
 10. A measuring sensing device according to claim2, characterized in that the rotor means is supported at the statormeans by way of an friction bearing means which guides the rotor meansin the radial and axial directions.
 11. A measuring sensing deviceaccording to claim 1, characterized in that the rotor means is supportedat the stator means by way of at least one friction bearing means.
 12. Ameasuring sensing device according to claim 11, characterized in thatseparate friction bearing means in the form of slide bearings areprovided for the radial and axial guidance.
 13. A measuring sensingdevice according to claim 2, characterized in that the rotor and statormeans are provided at mutually opposite end-faces with end-face toothmeans tHat do not contact one another.
 14. A measuring sensing deviceaccording to claim 13, characterized in that an axial friction bearingmeans is formed by layers of non-magnetic friction bearing materialapplied to the end-face tooth means so that a certain axial distance ofrotor and stator means is determined by the layer thicknesses over thetooth tips.
 15. A measuring sensing device according to claim 14,characterized in that a radial friction bearing means is formed bylayers of non-magnetic friction bearing material applied over the toothmeans.
 16. A measuring sensing device according to claim 2,characterized in that at least one of the two parts consisting of rotorand stator means essentially consists of a synthetic resinous materialcontaining iron.
 17. A measuring sensing device according to claim 2,characterized in that both rotor and stator means are made fromiron-containing synthetic resinous material.
 18. A measuring sensingdevice according to claim 2, characterized in that at least one of therotor and stator means is partially magnetized.
 19. A measuring sensingdevice according to claim 2, characterized in that both rotor and statormeans are partially magnetized.
 20. A measuring sensing device accordingto claim 18, characterized in that only the counter element formed ofthe other of the two parts consisting of rotor and stator means isprovided with a toothed means.